According to the state of the art it is known to provide domestic appliances, especially hair care devices, comprising an ion source for emitting ions. Recently, hair care devices, e.g. hairdryers, hairbrushes or curling irons, having the function to expel ionized particles, i.e. negatively ionized air or positively ionized air, have enjoyed increasing popularity. These devices make it possible to obtain the effect of treating the hair, making it more manageable and giving it more body, by expelling towards the hair the negatively or positively ionized air while drying, brushing or curling the hair.
It is further known to provide apparatuses, which are able to count ions emitted by an ion source. Usually, such apparatuses count the number of ions and measure the concentration of ions, respectively, in a gas medium by means of electric current detection with an electrometer or another current detecting device. Such apparatuses usually comprise a so-called Faraday cup being made of a conductive material and having a relatively small input opening. In order to count the ions, the Faraday cup is positioned such that a narrow ion beam, which may for example be expelled by a directional ion source, enters the cup via the input opening. Alternatively, air of the environment could be sucked through the input opening, so that the ions in the surrounding gas medium are sucked into the Faraday cup as well. Inside the Faraday cup the ions, which carry an electric charge, impinge on its inner surface such that a current could be measured by means of the electrometer which is coupled with the Faraday cup. The measured current is directly proportional to the number of ions and number of charges per ion, such that it could be used to determine the number of ions emitted by an ion source and collected by the Faraday cup.
The known apparatuses for counting the number of ions emitted by an ion source have proved themselves insofar as the number of ions emitted by a directional ion source could be reliably determined by leading the ion beam of a directional ion source directly through the input opening into the Faraday cup. However, it has been found out that the result of the measurement is less accurate if the ions are emitted by a non-directional ion source and have to be taken up through the input opening by sucking the environmental air of the non-directional ion source through the input opening.
It is therefore an object of the present invention to provide an apparatus for counting the number of ions emitted by an ion source of a handheld domestic appliance permitting an accurate and reliable counting of the emitted ions independent of the type of ion source. It is a further object of the present invention to provide a method for counting the number of ions emitted by an ion source of a handheld domestic appliance permitting an accurate and reliable counting of the emitted ions independent of the type of ion source. Above this, it is an object of the present invention to provide an advantageous use of the apparatus and the method according to the invention.